Music industry trade body, the BPI, said it would take legal action if the telecoms firm refused to co-operate.

The movie industry has already forced BT to block Newzbin 2, a members-only site that aggregates illegally copied material.

BT said: "We can confirm we are now in receipt of a letter from the BPI. BT is considering its response."

The telecoms operator added that a court order would be needed before any blocking could begin.

A source told the BBC the firm was unlikely to fight a lengthy legal battle as it had in the Newzbin case.

"We would not tolerate Counterfeits 'R' Us on the High Street - if we want economic growth, we cannot accept illegal rip-off sites on the internet either," said the BPI's chief executive, Geoff Taylor.

Richard Mollet, chief executive of The Publishers Association added: "It is crucial that the creative sector keeps up the momentum of getting internet companies to do their bit in tackling illegal sites."